<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>02_resize</title>
    <style>
        .box1 {
            width: 400px;
            height: 400px;
            background-color: orange;
            resize: both;
            overflow: scroll;
        }
        .box2 {
            width: 800px;
            height: 600px;
            background-color: skyblue;
        }
    </style>
</head>
<body>
    <div class="box1">
        <div class="box2">123</div>
    </div>
</body>
</html>